Cervical Plexus Block
The cervical plexus block is probably most often associated with analgesia for carotid endarterectomy surgery. However, its utility branches into other procedures as well. It has been cited in recent literature as being useful in clavicle, airway, thyroid and submandibular surgeries, as well as neck dissections. It has also been indicated in certain headache treatments. While the innervation and anatomy of the neck are complex (to say the least), the block itself is relatively simple. With a few points of caution, it can be utilized safely and easily. The cervical plexus block is really describing three separate regions; the deep, the intermediate and superficial cervical plexus. The deep and superficial blocks are well understood and described, but the intermediate block is not as well studied. Since the peer reviewed intermediate cervical plexus block literature is scarce it is not covered here. Many times the deep and superficial cervical plexus’ are blocked in combination to produce analgesia to the peri-clavicular and neck region. In fact, studies suggest that combining deep and superficial plexus blocks provide better analgesia than single blocks alone. Interestingly, this is one of the few techniques that ultrasound guidance fails to show any benefit with regard to success rates, however, the indication of reduced intravascular and unintended nerve contact are now well appreciated. When considering total regional anesthetic for these procedures, it is important to confer with the surgeon, and inform the patient that supplemental infiltration may be required to complete the surgery.
Distribution of the superficial cervical plexus
It should be noted that the phrenic nerve (lying just posterior to the great vessels), vagus nerve (lying between the internal jugular and carotid artery) and great vessels of the neck all lie in close proximity to the target structures for this block. Careful aspiration and slow careful injections will help avoid catastrophic nerve injury and intravascular injection. Immediately stopping if the patient complains of pain is extremely important.
The procedure for blocking the superficial cervical plexus is relatively simple. The posterior border of the sternocleidomastoid (clavicular head) is prepped and marked. A small gauge needle is used to raise a skin wheel at the midpoint of the marked border. A long thin needle can then be used to infiltrate the entire line about 1/2-1 cm deep. The infiltration should be inferior as well as superior to the skin wheel. See gallery 15.1 to see these steps. A total of about 10 mLs of local anesthetic is deposited. The image below shows the landmarking and injection technique for the superficial cervical plexus block.
The deep cervical plexus derives branches from C-2 through C-4. To insure blockade of this distribution, the local must be placed near the anterior cervical roots. These roots may be encased in dura, so careful aspiration for CSF is very important to avoid a total spinal scenario. The landmarks for this block begin by identifying the mastoid process. A line connecting the mastoid process is then drawn to the base of the neck, about 1-2 cm posterior to the sternocleidomastoid muscle.
From this point a single injection of 10 mLs local anesthetic can be deposited via a transverse process block fashion, or each root may be infiltrated. Each transverse process should be palpable starting with C-2. A mark is placed where the process’ are felt down to C-4. Prep the area and raise skin wheels over the marks. A blunt needle is then used to contact the transverse process and then gently guided inferiorly to the bony structure. After careful aspiration about 5 mLs of local are deposited at each level. The image below shows proper placement of skin wheels after the transverse process’ have been marked. The posterior sternocleidomastoid border has also been marked for a superficial cervical plexus block. The image below shows the use of block needle for identifying and repositioning inferior to the transverse process of C-2. Careful aspiration and attention is paid to the patient’s response during the injection. See gallery 19.1 and 19.2 to see these steps.
Ultrasound guidance for the cervical plexus
Adding ultrasound guidance to the superficial cervical plexus can add vessel avoidance and visualization to the block. The technique can be done in short or long axis. The long axis may add the benefit of a more complete spread, but caution should be used with larger volumes as it can easily spread to undesirable yet, nearby location. The neck is then prepped with sterilizing solution. 5 mLs of lidocaine 2% with epinephrine was infiltrated at the posterior portion of the SCM border mark in an in plane orientation. A block needle is then placed in-plane after obtaining a long axis view of the posterior border of the SCM. This view is obtained with the linear transducer set to 2-3 cm. The entire needle is visualized as it passed along the SCM border. A hydro-dissection is performed using a solution of 10 mL of a long acting local like, ropivacaine 0.2%. This block can be extended by the application of Exparel, such as 10ml exparel, mixed with 5 ml marcaine, diluted with 5 ml of saline or LR. This yields 20 ml, for either, bilateral superficial plexus block (example for neck lift in plastic surgery) or to be used in combination with a unilateral deep cervical plexus block.This is done along the superficial cervical plexus plane. See gallery 15.3 to see the steps and sonograms for the long axis, in-plane superficial cervical plexus block. See video 15.1 to see an actual needle placement for this technique. The short axis view can also be used to complete this technique. The advantage of this view is that it shows the relevant structures in the neck such as vessels and nearby nerves that may be undesirable to have contact with the needle or local solution. The scan begins simply, as you would for an interscalene, or stellate ganglion view. The great vessels of the neck are easily denoted. Following prep and skin local infiltration, the block needle is inserted in-plane behind the posterior border of the SCM.